Electronic data storage devices provide access (storage and retrieval) to data under the control of electrical signaling. Many different recording mediums exist for storing the data, each having different characteristics and parameters. Memories used in data storage devices can be classified into volatile memories and non-volatile memories. Non-volatile memories, e.g., those using magnetic recording media or floating-gate transistors, maintain stored data in the absence of electrical power. Volatile memory, such as Dynamic-Random-Access-Memory (DRAM) or Static-Random-Access-Memory (SRAM), will lose stored data when electrical power is removed.
Magnetic-based memory stores data by magnetizing a magnetic recording medium in a particular orientation. Data is read by passing a sensor over the magnetized areas to detect the orientation of the stored magnetic fields. A use for magnetic recording media is to position read-write heads near rotating magnetic platters. Magnetic recording media have the advantage of being non-volatile due to the use of a magnetized medium, which does not require electrical power to maintain stored-data integrity.
Solid-state memory refers to devices that use semiconductor technology as the storage medium. One type of solid-state memory is non-volatile flash memory. Non-volatile flash memory operates by storing charge on a floating gate of a memory cell. In particular, non-volatile flash stores data by charging a floating gate that maintains the stored charge in the absence of electrical power. Flash memory also has the added benefit of not being as susceptible to mechanical perturbations because it does not require movable parts to access the storage medium.
A particular field of use for both solid-state memory and magnetic-based memory relates to storage devices accessible by electronic systems, and more particularly, computer systems. For example, a conventional hard disc drive (HDD) includes a rotating magnetic media that is accessed under the control of electrical signals provided by an electronic control circuit. Another type of data storage device is a solid-state device/drive (SSD) that uses solid-state memory accessed under the control of electrical signals. When viewed from a programming or memory-hierarchical perspective, HDDs and SSDs can look similar or even identical. From a practical standpoint, however, these drives often exhibit a number of important differences including, but not limited to, access speeds, power consumption, reliability and susceptibility to data loss due to mechanical vibrations or sudden power loss.
For a variety of reasons, (e.g., access times or wear from erasure cycling) accesses (reads or writes) to HDDs and SSDs can be facilitated using a volatile memory for temporary storage during normal operation of the HDD or SSD. Traditional HDDs and SSDs receive their primary operating power from an external source, such as the computer system that accesses the data stored therein. Before shutdown of the HDD/SSD, data from the volatile memory can be stored/written to the non-volatile memory. A sudden/unexpected loss of power from the external source, however, may require a local/backup source of energy to prevent data in the volatile memory from being lost. HDDs can utilize the kinetic energy from the spindle motor to briefly maintain drive supply voltages in the event of an unexpected power loss. For example, back-electromotive force (EMF) is converted into electrical power and the drive is allowed to write data from a temporary/volatile cache to the non-volatile rotating magnetic media. The lack of rotating media in SSDs results in alternative solutions, one of which is the use of a backup power supply. The backup power supply provides energy that facilitates transfers of data from the volatile memory to the non-volatile memory in the event of a loss of power.
Improvements and applications relating to these and other aspects of storage devices are contemplated.